Determining device state using a state-detection circuit

An audio/video (A/V) hub includes a state-detection circuit coupled to at least one pin in a high-definition multimedia-interface input connector, which can electrically couple to an entertainment device. When electrically coupled to the entertainment device, the state-detection circuit establishes a ground loop between the electronic device and the entertainment device. A control circuit in the A/V hub detects whether there is electrical coupling with the entertainment device using the state-detection circuit. When the electrical coupling is detected, the control circuit provides a set of first control commands associated with different types of entertainment devices until, in response, content activity is detected via the input connector. Moreover, when the content activity is detected, the control circuit provides a set of second control commands associated with different providers of entertainment devices until a change in a state of the entertainment device is detected via the input connector and the state-detection circuit.